The present patent application has as its object the provision of a prosthetic band for repairing a mitral valve which incorporates notable innovations and advantages.
More specifically, the invention proposes the development of a prosthetic band designed to facilitate the repair of degenerative mitral insufficiency and having points of reference for the arrangement of artificial cords during the surgical operation.
At present, the main cause of impairment of the mitral valve is degenerative pathology bringing about mitral insufficiency.
The mitral valve is one of the four valves of the heart having a complex structure with various elements which must function in a coordinated manner in order to cause the blood to flow in the correct direction. If the closure of the valve is not adequate, this gives rise to so-called mitral insufficiency.
Basically, the valve consists of two leaflets (anterior and posterior) which are inserted on a ring and anchored to the papillary muscles of the wall of the left ventricle by a large quantity of chordae tendineae (see FIGS. 1 and 2), as can be seen in FIGS. 1 and 2. The normal mitral annulus 10 (see FIG. 4) has a posterior region and an anterior region situated between the two trigones, which are fibrous structures that form part of the base of the heart.
Under normal conditions, during the contraction phase of the heart, those two leaflets come together (coaptation zone) and close the valve, preventing insufficiency from occurring. The closure of the valve is produced practically at the level of the ring and never above it, given that the chordae tendineae do not allow the leaflets to rise above that level.
In mitral insufficiency of a degenerative origin, the closure of the valve is not correct because one of the leaflets, or both of them, move beyond the plane of the ring and penetrate partially into the left atrium, giving rise to what is referred to as prolapse of the leaflets. The primary cause of the prolapse is the elongation or rupturing of one of more of the chordae tendineae.
The most common prolapse is that of the posterior leaflet, but prolapses of the anterior leaflet or of both simultaneously are also common. Relevantly, in mitral insufficiency there always exists a dilatation of the mitral annulus to varying degrees.
When the mitral insufficiency is severe, the patient must undergo surgical intervention. The possibilities are the replacement of the valve with an artificial valve prosthesis, or the repair of the valve itself.
Currently, there is clear evidence that repair is superior to the replacement of the valve in terms of survival, reduction of complications and improvement of the functional status of the patient.
The correct repair of the mitral valve has three objectives:
To restore the mobility of the leaflets without restriction or excess movement;
To create an adequate coaptation surface or closure;
To remodel the shape and size of the dilated mitral annulus.
The repair of the isolated prolapse of the posterior leaflet is simple and reproducible and has traditionally been treated through partial resection of the leaflet. However, when the prolapse is of the anterior leaflet or of both leaflets, the difficulty increases, and many surgeons are unable to repair the valve.
One known and widely used technique consists of the use of artificial cords (hereinafter called “neocords”), usually made of PTFE, which substitute the torn or stretched chordae tendineae. These neocords are stitched to the papillary muscles and extend to the free edge of the leaflets and imitate the function of the natural cords.
The artificial neocords made of PTFE have become the technique of choice for correcting mitral prolapse, and its use has therefore become widespread. Such neocords enable the repair of prolapses of one or both leaflets or of multiple prolapsing segments of the same leaflet, applying as many neocords as necessary.
Nonetheless, the use of these artificial cords is associated with two significant technical problems. One of them consists in the difficulty in measuring the exact shape of the length that the artificial neocords must have, while a second known problem is related to the difficulty in tying the cords over the leaflet while preventing the knots from sliding downward (resulting in the cord being shorter than required and causing overcorrection) due to the slippery nature of the PTFE material.
Various attempts have been made to resolve the aforementioned problems.